There is an increasing demand for electrical power in large aircraft as hydraulic and mechanical systems are replaced with electrical components distributed lengthwise along the aircraft. One or more generators located centrally may provide a main power for flight control, passenger comfort, safety, and other systems. In addition, a battery source may provide backup power for emergency loads should the main source fail. Some of these emergency loads are designed to operate directly at a battery voltage, such as at 28V DC, which may be lower than a generator voltage. Unfortunately, the heavier weight of the electrical wires distributing a relatively higher current to the emergency loads may reduce aircraft payload or performance.
One method of preserving aircraft performance and accommodating the increasing electrical demand of today's aircraft is to distribute current from a centralized generator to each emergency load at a relatively high voltage and then down-convert the voltage near each low-voltage load. Advantageously, this reduces the weight of main-power wiring and incorporates a redundant path for the distribution of battery backup power to each load. Unfortunately, heavy wiring is still required to distribute battery backup power from a centralized battery to the emergency loads distributed throughout the aircraft. Additionally, a second voltage converter may be needed at each emergency load, one for main power and one for backup power, adding more weight to the aircraft.